Blog

Loose tube: Your fiber cable choice depends on your application

You know what's in loose tube fiber cable? A bunch of loose tubes filled with fiber. Makes sense, doesn't it? Now that we have that out of the way …

This is the 12th in a Telect blog series, entitled The ABCs of Cable Management. Product Manager Peter Adams explores the difference between loose tube and tight buffered fiber optic cable.

Choosing the right type of cable is dependent on your network application. You need to protect the fiber from stress and environmental damage, during installation and maintenance.

When you're talking about outdoor network infrastructure, we have to consider the fiber is exposed to:

Temperature changes

Wind

Lightning

Weight from snow and ice

Moisture

Rats … yes, chewing rats

Your fiber optic cable has to be tough, but you have to make the choice between loose tube and tight buffered.

What's inside that loose tube cable

The loose tube buffering design isolates the fiber from these stresses, guarding the glass — and your signal — in rigid protective sleeves and a sturdy outer jacket.

When you cut open a single loose tube cable, you find:

A ripcord for splitting the outer jacket

Fiberglass yarn

Water-blocking tape, powder or gel

Binding tape

Buffer tubes

A single strength member

It all protects the fiber core, cladding and coating.

Because the fiber is not connected to the buffer tubes, the cable can be pulled and stretched without causing any fractures from bending or tension.

Because of its resistance to environmental damage, loose tube is ideal for outdoor applications. It can be used in conduits, strung overhead or buried underground.

Why not choose tight-buffered cable?

Tight-buffered cables, on the other hand, are optimal for indoor applications. While they have a sturdier build, they are best suited for medium-length LAN//WAN connections, long indoor runs and even underwater environments.

Instead of the water-blocking tape or gel, tight-buffered cables have a two-layer coating, one plastic and one waterproof acrylate. The core of the cable is never at risk of exposure, unlike the loose-buffered cable which can escape its confines.

It's more flexible than loose tube and can be used in outdoor applications but its plastic buffer, which is directly attached to the fiber, does not protect the glass from stretching and bending.

Tight-buffered cable is best for very controlled conditions where bend radius standards are tightly maintained and runs are short enough to minimize attenuation.

What's your decision

It looks like the choice is easy. Both loose tube and tight-buffered fiber cable have their advantages and disadvantages.

The choice is dependent upon your network environment and how easy you need to make your life during installation and maintenance.

Peter Adams is a Product Manager at Amphenol Telect. He joined the company three months ago and is eager to learn all he can about the fiber optic network industry.